This invention relates generally to the field of surface roughness measurement, and more particularly to the determination of the extent of fouling by marine growth on a ship hull, and the hydrodynamic effect thereof.
Inspection of ship hulls to determine the condition thereof has generally been carried out visually be divers. Limited use has been made of profilometers adapted to underwater use, of stereophotogrammetry, and of surface impressions taken with clay or other plastic material.
Determinations made by those techniques provide, of course, certain valuable information. However, translation thereof to provide an interpretation of the hydrodynamic effect of the condition on hull performance is largely subjective, colored by experience of the investigator and, at best provides an unreliable measure of hull condition.
There has existed a need for a diagnostic tool that could be used by divers to obtain a rapid, direct, and reliable measure of the degree of ship hull fouling and its effect on the performance of the vessel.
Various devices have been proposed for testing or measuring the degree of roughness of the surfaces of materials. In addition to profilometers, mentioned above, pneumatic devices have been proposed that measure roughness by detecting the amount of air flow from a nozzle or sensing head disposed against the surface to be tested. While those devices are suitable for determining roughness of paper or the like, they are not adaptable to the problem, addressed by the present invention, of determining marine fouling and other roughness producing conditions of ship hulls, such as rust, corrosion, and coating deteriorations, while in the water, and of measuring the hydrodynamic effect thereof.